Failure and Embarrassment
When I go out to shoot photos I sometimes feel a little self-conscious about people seeing me out with a 35mm SLR, 35mm rangefinder, or my medium format setup and thinking that I am one of those "hipsters" doing it for the "cool factor". I think this has come from me (unfortunately) meeting people like this who are just into film because they think it will give their photos a "vintage" look. It just so happens that these people consistently put out horrible photographs trying to achieve that "look" of dirty, old, scratched up, washed out photos full of artifacts and imperfections.
Rather than film or digital, and possible accusations of hipsterism, you are probably feeling more self conscious about doing what it really takes to make great photographs, and that is risking failure and embarrassment.
Failure: even the best photographers miss the target more often than not. Look at any photographer's contact sheets and see how often they "fail forward" in searching for just the right angle or expression. That moving and searching is often very physical, with a lot of crouching or knee-bending. Especially with medium format, you can start to look like a hunchbacked weirdo!
Embarrassment: you have to put yourself out there, and be willing to walk up to a complete stranger and say "can I make a photograph of you?" I've done this quite a lot, and I would say that 95% of people answer "yes." They are flattered. You've played to their ego. They want to know why you would select them out of a crowd. But the risk is that they will say no, and think you are a freak.
On some of my projects I used to give a long winded explanation. Now, I say simply "I'm working on a book of Rodeo photographs." Talk about an in! I'm going to make your photograph and it might be in a book. Yes! Let's do it! People really respond to that.
Last week, I was crawling around in a neighbor's yard, photographing a cluster of mushrooms that had popped up overnight. It was ungodly hot, I was dripping with sweat, and cars kept rolling by at 5 miles an hour to see what was up. Every time, I would just turn and wave and give them a big old smile.
It seems weird, but it lets people know that you are having a great time, doing exactly what you want to be doing, and that you are not afraid to be seen doing it (as you would if you were a perv or something).
And I can't tell you how many times people have seen my Bronica and said "oh, you're a REAL photographer!"
So, take the risks. When you get the reward of great photographs, everything else will seem far less important.